Cytisus-scoparius
Guides
Bruchidius villosus
broom seed beetle, Scotch broom bruchid
Bruchidius villosus is a small seed-feeding beetle in the family Chrysomelidae, native to Europe and introduced to North America and New Zealand as a biological control agent for Scotch broom (Cytisus scoparius). It has been deliberately released in the United States since the 1990s to reduce seed production in this invasive weed. In New Zealand, it has exhibited problematic host range expansion to non-target leguminous plants. The species is approximately 2 mm in length with dark gray coloration.
Ctenocallis setosa
Ctenocallis setosa is a small aphid species native to Europe, adventive in North America, and recently detected in Japan (2017–2018, 2023–2024) as the first record for Asia. It is tightly associated with Cytisus scoparius (scotch broom), a naturalized invasive shrub. The species exhibits a monoecious holocyclic life cycle with sexual morphs produced in fall for overwintering eggs and no summer host alternation.